Wavefront interferometry is a standard solution when measuring optical surface error or wavefront aberrations. However, the lateral range of measurement is usually limited by the aperture of the interferometer. Subaperture stitching interferometry solves this problem by dividing the full aperture into a series of smaller, overlapping subapertures that are measured individually before being stitched back together. This Spotlight introduces the mathematical background, stitching algorithms, and subaperture lattice design for stitching interferometry with null subapertures, non-null subapertures, and near-null subapertures as applied to large flats, high-numerical-aperture spheres, and aspheres.